A group of researchers at Case Western Reserve University, Cleveland, Ohio, allowed a paralyzed person to stand up for two minutes in 2006 by electrically stimulating nerves that fired into the muscles attached to the patient’s knees. Now, they’ve gone a step further toward developing leg control for people with paralysis by stimulating a different patients’ femoral nerve trunk, independently twitching four of the major muscles that allow for independent standing.
“We tested the hypothesis that a flat interface nerve electrode (FINE) placed around the femoral nerve trunk can selectively stimulate each muscle the nerve innervates,” wrote a team led by Case Western neural engineer Matthew Schiefer, PhD, in the April 2010 Journal of Neural Engineering. “In a series of intraoperative trials during routine vascular surgeries, an eight-contact FINE was placed around the femoral nerve between the inguinal ligament and the first nerve branching point. The capability of the FINE to selectively recruit muscles innervated by the femoral nerve was assessed with electromyograms (EMGs) of the twitch responses to electrical stimulation. At least four of the six muscles innervated by the femoral nerve were independently and selectively recruited in all subjects. Of these, at least one muscle was a hip flexor and at least two were knee extensors.”
According to an April 1 article in New Scientist magazine, the 2006 experiment used electrodes placed on the nerve’s surface and held in place with a spiral cuff. The FINE is instead “a cuff that squashes a nerve flat to bring fiber bundles closer to the surface and to the eight electrodes in the device’s soft rubber lining.” The nerve twitches the FINE generated weren’t long enough to have allowed an unsedated patient to stand, but Schiefer’s team suspects that longer pulses to the same nerves might. According to New Scientist, the researchers are currently seeking U.S. Food and Drug Administration (FDA) approval for more involved trials of the method.
